Hormonal and tissue-specific control of the aromatase cytochrome P450 (CYP 19) gene is obligatory for the synthesis of estradiol and proper function of the female reproductive system. Expression of aromatase by ovarian granulosa cells is regulated in a cAMp-dependent manner by the peptide hormones, fSH and LH via the protei n-kinase A pathway. In addition, expression of aromatase in the rat is exclusively localized to the ovary, testis and brain. This proposal focuses on identifying cis-acting DNA elements and trans-acting factors that mediate the cAMp-dependent as well as tissue-specific expression of aromatase in the rat ovary. Use of electrophoretic mobility shift assays as well as transient transfection of ovarian granulosa cells with aromatase promoter CAT reporter constructs will allow me to determine the function of specific regulatory regions of the promoter and the proteins that bind to these promoter elements. Determination of genomic sequences necessary for tissue-specific expression of aromatase will be investigated by generation of transgenic mice. Results obtained from these studies will provide basic information concerning the transcriptional regulation of the rat aromatase promoter by cAMP and identify the regions required for tissue-specific expression of the aromatase gene in vivo.